Power amplifier linearization methods and apparatus using predistortion in the frequency domain
First Claim
Patent Images
1. A method comprising:
- predistorting an input signal to a power amplifier generating a non-linear output, the predistortion being performed in the frequency domain by modifying frequency-domain symbols used to modulate individual sub-carriers of an orthogonal frequency division multiplexed signal;
wherein modifying the frequency-domain symbols comprises replacing one or more frequency-domain symbols with frequency-domain predistortion symbols.
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Abstract
To mitigate the effects of non-linear amplification in a digital transmission system employing a multi-carrier multiplexing communications technique, such as orthogonal frequency division multiplexing or discrete multi-tone, predistortion of an input signal to a power amplifier with a non-linear transfer characteristic is performed in the frequency domain by modifying frequency-domain symbols used to modulate individual sub-carriers. The frequency-domain symbols are modified in a manner that compensates for the amplifier'"'"'s non-linear transfer characteristic.
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Citations
46 Claims
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1. A method comprising:
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predistorting an input signal to a power amplifier generating a non-linear output, the predistortion being performed in the frequency domain by modifying frequency-domain symbols used to modulate individual sub-carriers of an orthogonal frequency division multiplexed signal; wherein modifying the frequency-domain symbols comprises replacing one or more frequency-domain symbols with frequency-domain predistortion symbols. - View Dependent Claims (2, 3, 4)
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5. A method comprising:
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encoding a stream of input bits into a plurality of frequency-domain symbols, wherein each symbol comprises a complex number representing a plurality of the input bits; transforming a block of the frequency-domain symbols into a time domain to generate samples of a time-domain waveform representing a sum of orthogonal carrier waveforms, with each carrier waveform being modulated by a frequency-domain symbol; converting the time-domain waveform samples into an analog waveform to drive a power amplifier in order to transmit the analog waveform over a communications channel; predistorting the time-domain waveform samples by modifying the frequency-domain symbols before transformation into the time domain; and modifying the frequency-domain symbols by replacing one or more frequency-domain symbols with frequency-domain predistortion symbols. - View Dependent Claims (6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. A system comprising:
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a power amplifier to be responsive to an orthogonal frequency division multiplexed input signal and to generate an output signal having a non-linear transfer characteristic; circuitry to produce predistortion of the input signal, the predistortion being performed in the frequency domain by modifying frequency-domain symbols used to modulate individual sub-carriers of the input signal; and an omnidirectional antenna coupled to the power amplifier to receive the output signal; wherein modifying the frequency-domain symbols comprises replacing one or more frequency-domain symbols with frequency-domain predistortion symbols. - View Dependent Claims (23, 24)
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25. A system comprising:
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a modulator to encode a stream of input bits into a plurality of frequency-domain symbols, wherein each symbol comprises a complex number representing a plurality of the input bits; an inverse-discrete-Fourier transformer to process a block of the frequency-domain symbols to generate samples of a time-domain waveform representing a sum of orthogonal carrier waveforms, with each carrier waveform being modulated by a frequency-domain symbol; a digital-to-analog converter to convert the time-domain waveform samples into an analog waveform; a power amplifier to transmit the analog waveform over a communications channel; and a predistorter to modify the frequency-domain symbols before inverse-discrete-Fourier transformation in a manner that compensates for a non-linear transfer characteristic of the power amplifier, wherein the predistorter is to modify the frequency-domain symbols by replacing one or more frequency-domain symbols with frequency-domain predistortion symbols. - View Dependent Claims (26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37)
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38. An article comprising a machine-accessible medium having associated information, wherein the information, when accessed, results in the machine performing:
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encoding a stream of input bits into a plurality of frequency-domain symbols, wherein each symbol comprises a complex number representing a plurality of the input bits; inverse-discrete-Fourier transforming a block of the frequency-domain symbols to generate samples of a time-domain waveform representing a sum of orthogonal carrier waveforms, with each carrier waveform being modulated by a frequency-domain symbol; and predistorting the time-domain samples by modifying the frequency-domain symbols before inverse-discrete-Fourier transformation in a manner that compensates for a non-linear transfer characteristic of a power amplifier; wherein modifying the frequency-domain symbols comprises replacing one or more frequency-domain symbols with frequency-domain predistortion symbols. - View Dependent Claims (39, 40, 41)
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42. A method comprising:
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predistorting an input signal to a power amplifier generating a non-linear output, the predistortion being performed in the frequency domain by modifying frequency-domain symbols used to modulate individual sub-carriers of a multi-carrier wireless communications channel; wherein modifying the frequency-domain symbols comprises replacing one or more frequency-domain symbols with frequency-domain predistortion symbols. - View Dependent Claims (43, 44, 45, 46)
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Specification